Saudi Arabia tackles MERS virus, still hunting source

LONDON Nov 21 (Reuters) - Saudi Arabia has not yet traced the source of a mysterious camel virus, leaving many questions about a disease that has killed 346 people in the Kingdom.

The lack of scientific evidence about how camels contract the virus, which causes an often fatal illness called Middle East Respiratory Syndrome (MERS) in people, echoes wider concerns about the threat posed to human health by animal-borne pathogens, including the Ebola virus.